@fluojs/queue

@fluojs/queue

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Redis-backed distributed job processing for fluo. It features decorator-based worker discovery, JSON-safe job serialization, and lifecycle-managed execution.

Table of Contents

• Installation
• When to use
• Quick Start
• Common Patterns
• Public API
• Related Packages
• Example Sources

Installation

npm install @fluojs/queue @fluojs/redis

When to Use

• When you need to process long-running or resource-intensive tasks in the background.
• When you want to decouple expensive operations (e.g., sending emails, image processing) from the request-response cycle.
• When you need a distributed queue with retry logic, backoff, and dead-letter handling.

Quick Start

1. Define a Job and Worker

Create a job class and a worker class decorated with @QueueWorker.

import { QueueWorker } from '@fluojs/queue';

export class ProcessOrderJob {
  constructor(public readonly orderId: string) {}
}

@QueueWorker(ProcessOrderJob, { attempts: 3, backoff: { type: 'fixed', delayMs: 5000 } })
export class OrderWorker {
  async handle(job: ProcessOrderJob) {
    console.log(`Processing order: ${job.orderId}`);
    // Your logic here
  }
}

2. Register and Enqueue

Import QueueModule and inject QueueLifecycleService to enqueue jobs.

QueueModule.forRoot(...) is the supported root entrypoint for application-level queue registration.

import { Module, Inject } from '@fluojs/core';
import { QueueModule, QueueLifecycleService } from '@fluojs/queue';
import { RedisModule } from '@fluojs/redis';

@Module({
  imports: [
    RedisModule.forRoot({ host: 'localhost', port: 6379 }),
    QueueModule.forRoot(),
  ],
  providers: [OrderWorker],
})
export class AppModule {}

export class OrderService {
  @Inject(QueueLifecycleService)
  private readonly queue: QueueLifecycleService;

  async placeOrder(id: string) {
    await this.queue.enqueue(new ProcessOrderJob(id));
  }
}

Common Patterns

Named Redis Client

Leave clientName unset to keep using the default @fluojs/redis client from your app. If your queues should use a non-default Redis connection, set clientName to the name registered with RedisModule.forRoot({ name, ... }).

QueueModule.forRoot({ clientName: 'jobs' })

@fluojs/queue resolves that Redis client during application bootstrap, then creates queue-owned duplicate connections for BullMQ. The shared @fluojs/redis client remains owned by RedisModule; Queue closes only the duplicate BullMQ connections it creates. Those duplicate connections are configured with BullMQ's required maxRetriesPerRequest: null worker setting so startup behavior matches BullMQ's runtime constraints.

Distributed Retries

Workers can be configured with a maximum number of attempts and backoff strategies to handle transient failures automatically.

@QueueWorker(MyJob, { 
  attempts: 5, 
  backoff: { type: 'exponential', delayMs: 1000 } 
})

Dead-Letter Handling

When a worker exhausts its retry attempts, Queue appends a dead-letter record to Redis (fluo:queue:dead-letter:<jobName>) for manual inspection or recovery. Queue does not move the BullMQ job itself.

QueueModule.forRoot() keeps the most recent 1_000 dead-letter entries per job by default. Set defaultDeadLetterMaxEntries: false to opt out, or provide a smaller positive number when operators need a tighter retention budget.

Jobs must be JSON-serializable plain objects. Queue serializes the job payload before enqueueing and rehydrates the job prototype on the worker side.

Treat low-level provider assembly as an internal implementation detail: low-level provider helpers are not part of the documented root-barrel contract.

Public API Overview

Core

• QueueModule: Main entry point for queue registration.
• QueueModule.forRoot(options): Registers queue support for an application module.
• QueueLifecycleService: Primary service for enqueuing jobs (enqueue(job)).
• @QueueWorker(JobClass, options?): Decorator to mark a class as a job handler.
• QUEUE: Compatibility injection token for the queue facade.
• createQueuePlatformStatusSnapshot(...): Status snapshot helper for lifecycle/readiness diagnostics.

Types

• QueueModuleOptions: Global queue settings (clientName, default attempts, defaultBackoff, concurrency, rate limiting, dead-letter retention).
• QueueWorkerOptions: Per-job settings (attempts, backoff, concurrency, jobName, rate limiting).
• QueueBackoffOptions: Retry backoff settings (type, delayMs).

QueueModuleOptions also includes dead-letter retention controls such as defaultDeadLetterMaxEntries.

Only singleton @QueueWorker() providers/controllers are registered. Request/transient workers are skipped during discovery.

Related Packages

• @fluojs/redis: Required as the backing store for job persistence.
• @fluojs/cron: For scheduled/recurring background tasks.

Example Sources

• packages/queue/src/module.test.ts: Worker discovery and enqueueing tests.
• packages/queue/src/public-surface.test.ts: Public API contract verification.
• packages/queue/src/status.test.ts: Queue lifecycle status snapshot tests.